x.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <time.h>
#include <sys/select.h>
#include <string.h>
#include <libmnl/libmnl.h>

int main(void)
{
        struct mnl_socket *nl;
        char snd_buf[4] = {};
        struct nlmsghdr *nlh = snd_buf;
        unsigned int seq, portid;
        char buf[128];
        int ret;

        nlh->nlmsg_len = 80;

        nl = mnl_socket_open(NETLINK_NETFILTER);
        if (nl == NULL) {
                perror("mnl_socket_open");
                exit(EXIT_FAILURE);
        }
        if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
                perror("mnl_socket_bind");
                exit(EXIT_FAILURE);
        }
        portid = mnl_socket_get_portid(nl);

        ret = mnl_socket_sendto(nl, snd_buf, sizeof(snd_buf));
        if (ret == -1) {
                perror("mnl_socket_recvfrom");
                exit(EXIT_FAILURE);
        }
        printf("sent %d\n", ret);

        ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));

        printf("ret %d\n", ret);

        mnl_socket_close(nl);

        return 0;
}